Hundreds of local Catholic children scheduled to depart this morning for Sydney, Australia, for World Youth Day are instead stranded at the airport.

A special nonstop charter flight handled by Northwest Airlines was detained at Pittsburgh International Airport when a mechanical issue was discovered while fueling the aircraft. While the problem was being fixed, the flight's crew timed out. The flight is now rescheduled for 8 p.m., said airport spokeswoman Joann Jenny.

World Youth Day is organized by the Roman Catholic Church. The international event is held annually.